pmdomain: core: Fix error checking in genpd_dev_pm_attach_by_id()

pmdomain: core: Fix error checking in genpd_dev_pm_attach_by_id()

The error checking for of_count_phandle_with_args() does not handle
negative error codes correctly.  The problem is that "index" is a u32 so
in the condition "if (index >= num_domains)" negative error codes stored
in "num_domains" are type promoted to very high positive values and
"index" is always going to be valid.

Test for negative error codes first and then test if "index" is valid.

Fixes: 3ccf3f0cd197 ("PM / Domains: Enable genpd_dev_pm_attach_by_id|name() for single PM domain")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/aBxPQ8AI8N5v-7rL@stanley.mountain
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>